Method of treating fibrous materials



Feb. 17, 1931. F. w. BRODERICK I 1,792,805

METHOD OF TREATING FIBROUS MATERIALS Filed Aug. 22, 1927 I INVENTO R.ci'QedmLdg 7 3 5 .016

T TORNEYS.

Patented Feb. 17, 1931 UNITED STATES FREDERICK W. BRODER-ICK, 'QFOAKLAND, CALIFORNIA METHOD OF TREATING FIBROUS MATERIALS Applicationfiled August 22, 1927. Serial No. 214,626.

This invention relates to a method of treating fibrous materials derivedfrom a vegetable source, and particularly to a method whereby thefibrous material may be deodorized, sterilized and bleached.

The object of the present invention is to generally improve and simplifymethods of the character described, to provide a method whereby fibrousmaterials derived from a vegetablesource may be quickly and economicallydeodorized, sterilized and bleached, and especially to provide a methodwhereby fibrous materials in the form of lumber, sawdust, and the like,may be deodorized, sterilized and bleached by moistening the ma' terialwith an alkaline solution and then subjecting it to the action ofchlorine gas in such a manner that the reaction between the alkalinesolution and the chlorine gas forms an alkaline hypochlorite directly inand on the fibrous material.

For the purpose of clearly describing the invention reference will bemade to the accompanying drawing which diagrammatically illustrates oneform of apparatus that may be employed.

The method is applicable to practically any fibrous material obtainedfrom a vegetable source. Sawdust may be taken as an example, and brieflyspeaking, is treated in the following manner first, by moistening itwith a dilute alkaline solution, secondly, subjecting it to the actionof chlorine gas so as to form sodium hypochlorite directly in and on thesawdust particles, and finally washing and drying the sawdust. Numerousforms of apparatus may be employed, but I prefer to employ an endlessforaminated conveyor, such as indicated at 2. The sawdust to be treatedis placed on the conveyor and is passed under one or more sprinklers,such as shown at 3. A dilute alkaline solution is sprayed on thesawdust, and any excess delivered drains through the conveyor and isreceived by a tank 4. The solution employed is formed by dissolvingapproximately onehalf to one per cent by weight of sodium carbonate inwater. The solution is maintained in continuous circulation by means ofa pump or the like, indicated at 5. The sawdust,

when saturated, discharges from the end of the conveyor 2 into a hopper6 from where it is delivered into a tank 7, and When the tank is filledthe hopper opening is closed by a valve or the like, indicated at 8. Aperforated pipe 9 extends into the tank and this is connected with asource of steam by means of a pipe 10, and is also connected with asource of chlorine gas by means of a pipe 11. The steam is firstadmitted through valve 12 and the moistened sawdust is heated to anapproximate temperature of 100 F. The chlorinegas is then turned onby-opening the valve 14, and the valve is so regulated that sufiicientgas is admitted to react with the sodium carbonate present and therebyform sodium hypochlorite, the reaction taking place being substantiallyas follows:

The actual quantity of gas required is approximately .3 to .6 grams ofchlorine per pound of sawdust, and the time required is approximatelythree minutes, the reaction being rapid and the result being adeodorized, sterilized, bleached product. At the end of the operationthe sawdust is again subjected to the action of low pressure steam orwash Water to remove excess soda and chlorous compounds, the wash wateris drained off and the sawdust is removed and dried in a kiln, or thelike, in any suitable manner. The product finally obtained isexceedingly light in color, due to the bleaching action to which it hasbeen subjected, it is sterilized, and is in most instances substantiallyodorless.

Having thus described my invention, what I claim and desire to secure byLetters Patent 1s:

1. A method of treating a fibrous material derived from a vegetablesource, which consists in moistening the material with a dilute solutionof sodium carbonate, heating the moistened material to a temperatune ofsubstantially 100 F., then subjecting the material to the action ofchlorine gas to cause a reaction between the sodium carbonate and thechlorine to form an alkaline hypochlorite directly on the material, andthen washing and drying the material.

2. A method of treating fibrous material derived from a vegetable sourcewhich con- 5 sists in moistening the material with an alkaline solution,heating the material with steam and at the same time subjecting thematerial to the action of chlorine gas, thereby causing a transitoryformation of sodium hypochlorite and hypochlorous acid which, under theconditions of temperature break down, liberating nascent oxygen in thematerial which effectively bleaches, decolorizes and deodorizes thematerial.

FREDERICK W. BRODERICK.

